A typical form of known endoscope has a handle from which extends a flexible shaft terminating in a distal or operative end which is inserted into a body cavity to be inspected. Light is transmitted from the handle, through the shaft to the distal end where the light emitted illuminates the cavity to be inspected. The image to be viewed is transmitted back up the shaft to the handle which is equipped with an eyepiece for this purpose. The eyepiece includes a lens system which can be moved longitudinally by rotation of an adjusting ring in order to focus the image. For viewing the image by the eye, the user looks into the eyepiece and focuses the image for his eyesight by means of the adjusting ring.
It is desirable to have the facility of attaching a camera to the endoscope eyepiece, to enable the image to be photographed. The use of a camera requires that the image be brought into a predetermined position, even after the lens system has been adjusted to suit viewing by the eye. Hitherto this problem has been tackled by providing two adjusting rings each with a part-helical groove or cam track, one for adjusting the lens system for viewing by the eye and the other for adjusting the lens system for viewing by a camera.
The invention aims to provide a simpler arrangement requiring only one adjusting ring.